1. Technical Field
The present disclosure relates to an apparatus and method for thermal treatment of a tissue mass with radio frequency (RF) energy. In particular, the present disclosure relates to an apparatus for minimally invasive treatment of intramural leiomyomas.
2. Description of the Related Art
Myomas are currently the leading indication for surgery in women. A myoma is composed of muscle tissue. In women, a tumor of the uterus is a leiomyoma and may also be called a fibroid. Uterine leiomyomas are typically benign tumors located in the muscular layer of the uterus. These tumors affect 20-30% of women during their reproductive years. The highest rate of leiomyomas occur during the fifth decade of a woman's life. Depending on their size and location, leiomyomas can be asymptomatic or they can cause pelvic pain, dyspareunia, urinary problems or menorrhagia.
Currently, there are four types of therapy available to relieve a patient's symptoms due to a myoma: medical management, hysterectomy, myomectomy and myolysis. Medical management is the administration of hormone therapy which shrinks the myoma by inhibiting estrogen production. The disadvantages are adverse side affects and cost.
A hysterectomy involves the total removal of the uterus which can be performed by a variety of methods including laparotomy and vaginal or laparoscopic assisted vaginal hysterectomy (LAVH). The disadvantages of a hysterectomy are the elimination of fertility, long recovery period, early ovarian failure, urinary symptoms, fatigue, changes in sexual interest and function, depression, surgical complications, increase in the probability of developing cardiovascular disease and psychological loss of full womanhood.
A myomectomy procedure includes the removal of a myomatous tumor from the uterine wall. The disadvantages of the myomectomy procedure include treatment complexity in infertility, blood loss, time consumption and long postoperative care. Other complications include uterine perforation, delusional hyponoctrimia and thermos injury.
The above-mentioned invasive procedures for treatment of tumors are extremely disruptive and may cause damage to healthy tissue. For example, during the invasive surgical procedure, a physician must exercise care in not cutting the tumor in a manner that creates seeding of the tumor, which may result in metastasis. In recent years, product development has been directed towards minimizing the traumatic nature of traditional invasive surgical procedures by using non-invasive procedures.
A current non-invasive procedure is myolysis which reduces a myoma tumor mass by applying an electrosurgical cutting wave form with bipolar needles. Bipolar needles transfer localized current to the tissue between the needles. The thermal energy induced by the intrinsic effect of electric current necroses tumor tissue, denatures proteins and destroys vascularity of the myoma tissue. Subsequently, the myoma mass will atrophy if treatment is sufficient throughout.
Ideally, the clinical symptoms recede allowing a patient to return to normal activities. The benefits of myolysis include the advantages of laparoscopic surgery and further include absence of regrowth of the myoma tissue, minimized blood loss, preservation of the uterus, and a 41% reduction of tumor volume and reduction of adhesion formation compared to a myomectomy.
Myolysis may be accomplished either by laparoscopic methods or by endoscopic methods, such as transvaginal. The laparoscopic methods involve use of a cannula through which a myolysis tool may be introduced. The transvaginal approach may be through the cervix or through the fornix.
The presently available myolysis devices suffer from various drawbacks and disadvantages. For instance, sticking the electrodes into a myoma may cause trauma to the uterus upon penetration attempts into the myoma. This is particularly true in the single or dual bipolar needle devices which require multiple penetrations into tissue for complete ablation. U.S. Pat. No. 5,630,426 discloses single and dual bipolar needle devices for necrosis of a tumor.
An article by Dr. Herbert Goldfarb "Bipolar Laparoscopic Needles for Myoma Coagulation,"The Journal of the American Assoc. of Gynecologic Laparoscopis, February. 1995, reports that an average of thirty to fifty passes into different areas of a myoma with the bipolar needle is required in order to achieve complete tissue necrosis. Further, trauma is increased upon retraction of the device due to needle adhesion or sticking to surrounding structures and tissue. Additionally, needle devices of the prior art which rely on puncture-like penetration for insertion are known to deform because of the hard physical properties of a myoma.
Multiple needle devices are known for reducing the number of penetrations required for complete ablation of a tumor mass. U.S. Pat. No. 5,536,267 defines an apparatus that surrounds a tumor with a plurality of needle electrodes and defines an ablative volume. The '267 device, however, may pose a risk of damage or adhesions to surrounding structures because of the puncture-like penetration of the needles. This multiple needle approach has the disadvantage of moving the tissue mass upon insertion thereby affecting surrounding structures and tissue. Further, withdrawal of the needle electrodes from the desiccated tissue may pull on surrounding structures and healthy tissue causing damage thereto. Additionally, U.S. Pat. No. 5,697,909 discloses an electrosurgical probe having an array of isolated electrode terminals for treating structures within a body.
Accordingly, there is a present need in the state of the art for a needle electrode device that reduces the number of needle electrode penetrations required to ablate a tissue mass such as a myoma and further reduces the risk of damage or adhesions to surrounding healthy tissue and structures during needle electrode insertion and retraction. In the treatment of myomas, it is desirable that such a device reduces the risk of perforation of the uterus and damage to the serosa layer. Moreover, prevention of charring of tissue and tissue sticking to the needle electrode during coagulation, improved deployment into a tissue mass, minimized blood loss and speed of procedure are also desired.